An automotive closure, such as a door for an automobile passenger compartment, is hinged to swing between open and closed positions and conventionally includes a door latch that is housed between inner and outer panels of the door. The door latch functions in a well-known manner to latch the door when it is closed and to lock the door in the closed position or to unlock and unlatch the door so that the door can be opened manually. The door latch is operated remotely from inside the passenger compartment by two distinct operators--a sill button or electric switch that controls the locking function and a handle that controls the latching function. The door latch is also operated remotely from the exterior of the automobile by a handle or push button that controls the latching function. A second distinct exterior operator, such as a key lock cylinder, may also be provided to control the locking function, particularly in the case of a front vehicle door. Each operator is accessible outside the door structure and extends into the door structure where it is operatively connected to the door latch mechanism by a cable actuator assembly or linkage system located inside the door structure.
U.S. Pat. No. 5,277,461 granted to Thomas A. Dzurko et al on Jan. 11, 1997 for a vehicle door latch, which is hereby incorporated in this patent specification by reference, discloses a typical door latch. The door latch disclosed in the Dzurko '461 patent includes an inside latch operating lever that is pivotally mounted on a flange of a metal face plate and that is connected by a suitable linkage for rotation by an inside door handle (not shown). See column 4, lines 10-18 of the Dzurko '461 patent. The door latch also includes an inside lock operating lever that is pivotally mounted on the flange of the metal face plate near the inside latch operating lever. The inside lock operating lever is operated by an inside sill button or lock slide. See column 5, lines 46-58 and column 6, lines 8-15 of the Dzurko '461 patent. The door latch disclosed in the Dzurko '461 patent is released from the passenger compartment in two stages. First, the inside lock operating lever is rotated counterclockwise by an inside sill button or lock slide to unlock the door latch. Then, the inside latch operating lever 56 is rotated clockwise by an inside door handle to unlatch the door latch so that the vehicle door may be opened manually.
Door latches of the type disclosed in the Dzurko '461 patent have been used successfully by General Motors Corporation for many years.
Another vehicle door latch of General Motors Corporation is disclosed in U.S. Pat. No. 5,308,128 granted to Alfred L. Portelli and Rita M. Paulik on May 3, 1994 for a vehicle door latch that operates in a similar manner. The vehicle door latch disclosed in this patent, however, has a selectively activated security lock that prevents the door latch from being unlatched by an inside door handle or other inside operator. While this system is useful for many purposes, there are instances where it is desirable to allow passengers to unlock the door latch from inside the vehicle even though these passengers are not able to unlatch the door from inside the vehicle. While the vehicle door latch can often be unlocked by a sill button or an electric switch in the case of electric door locks, sill buttons are often difficult to operate by small children and an electric door lock may not be operable in case of a dead battery.